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keksAccountGUI/node_modulesOLD/regexp-tree/dist/interpreter/finite-automaton/nfa/builders.js

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2019-08-11 18:48:02 +00:00
/**
* The MIT License (MIT)
* Copyright (c) 2017-present Dmitry Soshnikov <dmitry.soshnikov@gmail.com>
*/
'use strict';
var NFA = require('./nfa');
var NFAState = require('./nfa-state');
var _require = require('../special-symbols'),
EPSILON = _require.EPSILON;
// -----------------------------------------------------------------------------
// Char NFA fragment: `c`
/**
* Char factory.
*
* Creates an NFA fragment for a single char.
*
* [in] --c--> [out]
*/
function char(c) {
var inState = new NFAState();
var outState = new NFAState({
accepting: true
});
return new NFA(inState.addTransition(c, outState), outState);
}
// -----------------------------------------------------------------------------
// Epsilon NFA fragment
/**
* Epsilon factory.
*
* Creates an NFA fragment for ε (recognizes an empty string).
*
* [in] --ε--> [out]
*/
function e() {
return char(EPSILON);
}
// -----------------------------------------------------------------------------
// Alteration NFA fragment: `abc`
/**
* Creates a connection between two NFA fragments on epsilon transition.
*
* [in-a] --a--> [out-a] --ε--> [in-b] --b--> [out-b]
*/
function altPair(first, second) {
first.out.accepting = false;
second.out.accepting = true;
first.out.addTransition(EPSILON, second.in);
return new NFA(first.in, second.out);
}
/**
* Alteration factory.
*
* Creates a alteration NFA for (at least) two NFA-fragments.
*/
function alt(first) {
for (var _len = arguments.length, fragments = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
fragments[_key - 1] = arguments[_key];
}
var _iteratorNormalCompletion = true;
var _didIteratorError = false;
var _iteratorError = undefined;
try {
for (var _iterator = fragments[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
var fragment = _step.value;
first = altPair(first, fragment);
}
} catch (err) {
_didIteratorError = true;
_iteratorError = err;
} finally {
try {
if (!_iteratorNormalCompletion && _iterator.return) {
_iterator.return();
}
} finally {
if (_didIteratorError) {
throw _iteratorError;
}
}
}
return first;
}
// -----------------------------------------------------------------------------
// Disjunction NFA fragment: `a|b`
/**
* Creates a disjunction choice between two fragments.
*/
function orPair(first, second) {
var inState = new NFAState();
var outState = new NFAState();
inState.addTransition(EPSILON, first.in);
inState.addTransition(EPSILON, second.in);
outState.accepting = true;
first.out.accepting = false;
second.out.accepting = false;
first.out.addTransition(EPSILON, outState);
second.out.addTransition(EPSILON, outState);
return new NFA(inState, outState);
}
/**
* Disjunction factory.
*
* Creates a disjunction NFA for (at least) two NFA-fragments.
*/
function or(first) {
for (var _len2 = arguments.length, fragments = Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
fragments[_key2 - 1] = arguments[_key2];
}
var _iteratorNormalCompletion2 = true;
var _didIteratorError2 = false;
var _iteratorError2 = undefined;
try {
for (var _iterator2 = fragments[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
var fragment = _step2.value;
first = orPair(first, fragment);
}
} catch (err) {
_didIteratorError2 = true;
_iteratorError2 = err;
} finally {
try {
if (!_iteratorNormalCompletion2 && _iterator2.return) {
_iterator2.return();
}
} finally {
if (_didIteratorError2) {
throw _iteratorError2;
}
}
}
return first;
}
// -----------------------------------------------------------------------------
// Kleene-closure
/**
* Kleene star/closure.
*
* a*
*/
function repExplicit(fragment) {
var inState = new NFAState();
var outState = new NFAState({
accepting: true
});
// 0 or more.
inState.addTransition(EPSILON, fragment.in);
inState.addTransition(EPSILON, outState);
fragment.out.accepting = false;
fragment.out.addTransition(EPSILON, outState);
outState.addTransition(EPSILON, fragment.in);
return new NFA(inState, outState);
}
/**
* Optimized Kleene-star: just adds ε-transitions from
* input to the output, and back.
*/
function rep(fragment) {
fragment.in.addTransition(EPSILON, fragment.out);
fragment.out.addTransition(EPSILON, fragment.in);
return fragment;
}
/**
* Optimized Plus: just adds ε-transitions from
* the output to the input.
*/
function plusRep(fragment) {
fragment.out.addTransition(EPSILON, fragment.in);
return fragment;
}
/**
* Optimized ? repetition: just adds ε-transitions from
* the input to the output.
*/
function questionRep(fragment) {
fragment.in.addTransition(EPSILON, fragment.out);
return fragment;
}
module.exports = {
alt: alt,
char: char,
e: e,
or: or,
rep: rep,
repExplicit: repExplicit,
plusRep: plusRep,
questionRep: questionRep
};